So if you want to renew it, you must to at least 3 sessions
Not true. The amount of refresher training is
entirely at the discretion of the ATO.
Also if you have done last time in the SIM you must renew it in the a/c
Also not true - the OP is talking about an MPA type rating.
Also I believe the UK actually has an exemption regarding the IR currency
Not a UK exemption, this is the case throughout Europe.
What will I need to renew the IR again in order to convert the UK jar license to EASA with the new rating and IR
Nothing. You already hold an EASA licence as all JAA licences are deemed to be EASA licences. The IR will be renewed as part of the type rating course, on completion of which you can apply for the new design EASA licence with the new type and renewed IR included.